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INTERACTIVITY
The Science
of Biology
CHAPTER
1
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Hydroponic plants
on the International
Space Station
1.1
What Is Science?
1.2
Science in Context
1.3
Patterns of Life
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6 Chapter 1 The Science of Biology

CASE STUDY
The continent of Antarctica has an average
annual temperature of −57°C (−70.6°F), and
no sunlight at all for months. During win-
ter, weather is so extreme that researchers
must be completely self-sufficient for at least
4months—because no supply flights dare to
reach the station except in life-or-death emer-
gencies. In most places, any soil that might
exist is buried beneath thick layers of ice and
snow. And visitors must be careful not to
introduce diseases or insects into the biologi-
cally pristine environment.
Yet, for nutritional reasons, scientists sta-
tioned at those stations need at least some fresh
produce in their diet. For psychological reasons,
it’s also helpful to have a little light and warmth
in their lives. How might biological knowledge
and technology work together under these
conditions? The answer is hydroponics.
As you probably know, most edible plants
normally grow in soil where roots anchor
the plants, and take up water and nutrients.
During the 1600s, scientists began trying
to grow plants in water. They soon learned
that plants grow better in water from natural
sources, such as ponds or rivers, than in pure
water. Later, they identified specific minerals
that plants need to thrive. And by the early
twentieth century, researchers successfully
raised crop plants in tanks of water enriched
with those nutrients.
Today, advanced hydroponic techniques,
including use of intense artificial light, enable
the crews of Antarctic research stations to
grow their own fresh fruits and vegetables.
Much of the research that developed those
techniques was sponsored by NASA (National
Aeronautics and Space Agency), because
hydroponics could provide fresh food for
astronauts on space missions, or for colonists
on Mars. In a more down-to-earth context,
some produce you buy in supermarkets—
including some lettuce and tomatoes—is
already grown hydroponically!
In theory, all you need to grow hydro-
ponic plants is a container of water with the
right nutrients, along with light and warm
temperatures. But during the long Antarctic
winter, there is virtually no sunlight available
at all! So providing the right kind and inten-
sity of artificial light is essential—as it would
be in space.
What steps did biologists and engineers
take to develop modern hydroponic tech-
niques? What other examples can you think
of where biology and technology were used
to solve a problem?
Throughout this chapter, look for
connections to the CASE STUDY to help you
answer these questions.
Biology is the science of life, the study of everything from molecules within living cells to
the effects of human activity on our planet. Biological knowledge can be combined with
technology to solve challenges, such as supplying fresh greens, fruits, and vegetables to
researchers in the Antarctic in the dead of the long, dark frozen winter.
Biology and technology solve problems
Unit 1 The Nature of Life 7

What Is Science?
1.1
LESSON
KEY QUESTIONS
• What are the goals of
science?
• What procedures are
at the core of scientific
methodology?
• What is a scientific
theory?
Humans have wondered about their place in the cosmos since the
earliest time. How do we fit into the grand scheme of nature? How
much power do we hold over nature? What are the limits to our abili-
ties? These and other questions are more relevant today than ever
before. This chapter begins our effort to show you how science tries
to answer those questions.
What Science Is and Is Not
This book will help you understand how biologists try to make sense
of nature. These pages are filled with many scientific “facts” and
ideas. But one of the first things you should understand is that sci-
entific knowledge is always changing. Some “facts” and ideas you’ll
find here may have changed since this text was written, and others
will change soon. Why? Because scientists are constantly testing,
debating, and revising scientific explanations of events in the natural
world. That constant testing and revising helps explain why scientists
don’t “believe” in scientific facts or ideas. Scientists either under-
stand and accept a particular scientific explanation of the natural
world, or they reject that explanation. But if science is not a list of
unchanging facts and beliefs, what is it?
The Nature of Science The term science is usually defined as
the use of evidence to construct testable explanations and predic-
tions of natural phenomena, as well as the knowledge generated
through this process. Most importantly, science is a process—an orga-
nized way of observing and asking questions about the natural world,
developing those questions into testable explanations, and gather-
ing and analyzing data that support or reject those explanations. The
word science can also refer to the constantly growing and changing
body of knowledge that the process of science generates.
What Is Science?
VOCABULARY
observation
inference
hypothesis
controlled experiment
independent variable
dependent variable
control group
data
theory
READING TOOL
List in order the parts of a
typical experiment that uses
scientific methodology.
Use the headings in your
text as a guide to fill in the
chart in your Biology
Foundations Workbook.
8 Chapter 1 The Science of Biology

1.1 What is Science? 9
How is science different from other ways of explaining how
the world works? First, science deals only with the natural world.
Scientific research never concerns, in any way, supernatural phenom-
ena of any kind. Second, scientists collect and organize information
in an orderly way, looking at events for patterns and connections of
cause and effect. Third, scientists propose explanations based on
evidence and understanding, not belief. Some ways that scientists
study the natural world are shown in Figure 1-1.
The Goals of Science Science is based on the view that the
physical universe is composed of interacting parts and processes.
From a scientific perspective, all objects in the universe, and all inter-
actions among those objects, are governed by universal natural laws.
The same natural laws apply whether the objects and events are
large (like a hurricane) or small (like the cells in your body).
Greek philosophers were among the first to try to explain the
natural world in terms of events and processes they could observe.
Modern scientists continue that tradition. One goal of science
is to provide natural and testable explanations for events in the
natural world. Science also aims to use explanations supported
by data to understand patterns in nature, and to make useful
predictions about natural events.
VIDEO
Discover how scientists use
scientific processes to dis-
cover the wide diversity of
insects that live in people’s
homes.
Figure 1-1
Studying the Natural
World
How do chimpanzees interact
with one another? What is the
ideal temperature for basil
plants in a hydroponics system?
What kinds of fish live in the
Colorado River? Researchers
can use science to answer these
questions and many others.
CASE STUDY
INTERACTIVITY

Science, Change, and Uncertainty Scientists have gath-
ered lots of important information that helps cure and prevent
disease, grow food, and link the world electronically. Yet much of
nature remains a mystery. Almost every scientific discovery raises
more questions than it answers. Often, research yields surprises that
point future studies in new and unexpected directions. This constant
change doesn’t mean science has failed. On the contrary, it shows
that science continues to advance.
That’s why studying science means more than just memorizing
what we know. It also means understanding what we don’t know. You
may be surprised to hear this, but science rarely “proves” anything.
Scientists aim for the best understanding of the natural world that
current methods can reveal. Uncertainty is always part of the scien-
tific process, and is part of what makes science exciting!
We hope to show you that understanding science isn’t just
about learning “facts.” We hope you’ll gain some understanding
of the spirit of scientific inquiry, of the way scientists think, and of
both the process and excitement of discovery. Don’t just memorize
today’s scientific facts and ideas. And please don’t believe them, just
because they are in a textbook! Instead, try to understand how sci-
entists developed those ideas. Pose the kinds of questions scientists
ask. Try to see the thinking behind the experiments we describe.
READING CHECK Construct an Explanation How is scientific
knowledge different from other types of knowledge?
Scientific Methodology
Is science a mysterious process that only scientists do under spe-
cial circumstances? Nope! You use scientific thinking all the time!
Suppose your family’s car won’t start. What do you do? You use what
you know about cars to ask questions. Is the battery dead? You test
that idea by turning the key in the ignition. If the starter motor works
but the engine doesn’t start, you reject the dead battery idea. Is the
car out of gas? A glance at the fuel gauge tests that idea. Again and
again, you apply scientific thinking until the problem is solved—or
until you run out of ideas and call a mechanic!
Scientists work in pretty much the same way. There isn’t a single,
cut-and-dried “scientific method.” But there is a general style of
investigation we call scientific methodology, which is a fancy way of
saying “the way science works.” Scientific methodology involves
observing and asking questions, forming hypotheses, conduct-
ing controlled experiments, collecting and analyzing data, and
drawing conclusions. Figure 1-2 shows how one research team used
scientific methodology in its study of one particular species of marsh
grass in a New England salt marsh.
INTERACTIVITY
Discover the power of
scientific methodology.
10 Chapter 1 The Science of Biology